The short answer is that there are many restrictions on government
agencies asking for your number, but few on individuals or companies.
When someone from a government agency asks for your number, they are
required to provide a Privacy Act
Disclosure Notice, which is required to tell you what law allows
them to ask, whether you have to provide your number, and what will
happen if you don't provide the number.

Private companies aren't required
to follow this law, and in general your recourse is to find another
company to do business with if you don't like their policies.

Why Should I
Care Whether Anyone Knows my SSN?

There are two problem with the way SSNs are used these days. The
first is that they are used (by different parties) as if they were both
a representation of identity and a secure password. The second problem
is that they have become a widely used identifier which can be used to
tie multiple records together about a single individual.

Many institutions, including hospitals and some banks and brokerages
use client's SSNs as a secure representation of their identity. This
seems a good idea, since you aren't allowed to change your SSN, even
though you might change your address, your name, or your phone number.
Other institutions, notably banks, use SSNs as if they were secret
passwords that only the owner would know. If someone knows the name and
the SSN, and is willing to say they have forgotten the account number,
they will usually be allowed to transfer funds, or make other changes
to an account with serious repercussions.

The problem is that these uses are incompatible. As SSNs are widely
used representations of people's identities, appearing on driver's
licenses, mailing labels, and publicly-posted progress reports at
universities, their broad availability becomes more apparent.

For the first few decades that SSN cards were issued, they carried
the admonition: "Not to be used for Identification." Unfortunately
there was never any law passed instituting this as a policy. The Social
Security Agency was apparently attempting to instill good values in the
citizens, but was apparently unsuccessful in preventing government
encroachment into this territory. For more information on the evolution
of the laws concerning privacy and Social Security additional details
are available in the more complete version of the FAQ.

Who has to have an SSN?

Do I have to get an SSN? Do I have to get an SSN for my
child?

The IRS says US Citizens who receive income are required to have an
SSN and employers are required to report income to the IRS using the
SSN. The written laws on this point are not very clear, and many people
who have read the law feel that the IRS is on shaky legal ground.
However, it's quite important to realize that your employer is quite
likely to believe the IRS when they say it is required over your claims
to have read the law and reached your own conclusions.

There are people who claim, based on nuances of the texts of the
laws that these IRS claims are incorrect and illegal. They point to a
single court case. As far as I can tell, these claims have not been
upheld more recently. The IRS continues to prosecute and harrass those
who attempt to resist having their incomes reported. I give pointers to
these claims, not because I believe them, but because I can't disprove
them. Caveat Lector: the IRS is willing to throw you in jail for
violating their interpretation of the laws. They are willing to shoot
you for resisting arrest. They have a separate court system, which
follows a different set of rules and procedures. Be sure that you
understand the potential consequences, and that you are willing to pay
the price before you enter this fight.

Seeking agreement and moral support, not all of the people
propounding these views will inform you fully of the potential
consequences of joining their fight.

Can I give up (renounce) my number?

As far as I can tell, the SSA doesn't recognize any procedure for
renouncing your SSN. The one exception I know of is that a parent who
can show that a number was assigned to their child without the parent's
consent can get the number removed from the SSA's records.

On the other hand, the SSA has no objection to your not revealing
your SSN as long as you do not engage in activities that bring you
under some legal compulsion to show it.

Depending on whether and how quickly you got it back, and whether
you suspect someone might have stolen your credit cards, driver's
license, or SS Card, different steps are called for. A complete guide
is available at the Privacy
Rights Clearinghouse.

Can I get a new number?

The Social Security Administration (SSA) will occasionally issue a
replacement SSN. This brief
guide will help you determine if you are eligible for a new
number

Someone is offering to get me a new SSN; is this legal?

The SSA doesn't seem to have set policies about issuing new SSNs. As
far as I can tell, they will only rarely issue a new SSN to someone who
has a significant problem with a stalker or identity theft. In either
case, you apparently have to convince someone at the local office that
you have tried all reasonable avenues for handling these problems, and
the problem continues to reappear because someone is tracking you
through your SSN, or because the identity thief continues to create new
false credit reports via misuse of your SSN.

If you can prove that you're being disadvantaged because someone
used your Social Security number, visit your local Social Security
office to request a new one. If you've done all you can to fix the
problem and someone is still using your number, under certain
circumstances, we may assign you a new number.

which seems not to promise anything, and to leave the discretion in
the hands of the local office. They do recommend that you file a report
with both Social Security Fraud Hotline at 1-800-269-0271 and the FTC.

There are quite a few companies offering to get you a new SSN to
help you escape credit problems. I haven't dealt with any of them, so I
can't report on this from personal experience, but I would be surprised
if any of them are doing anything that is both legal and valuable. The
only legal way to get a new number is to talk to the SSA, and they are
reluctant enough to issue a new number that you would have to deal with
them directly in order to legally get a new number. Another ploy
apparently used by these companies is to apply for a new number, make
one up for you, or apply for an employer's Tax ID number. All of these
are fraudulent, and unlikely to help you.

I would expect many of the people making these offers to be pure con
artists who would take your money, and not provide any service at all.
Since the service you are asking them to perform is illegal, they are
not very worried that their unsatisfied customers will report them to
the police.

A longer discussion and background information on this question can
be found here.

My long-lost brother's SSN is xxx-yy-zzzz. Can you help me find
his SSN?

I'm looking for my best friend from High School. How can I find
her?

This site is about Privacy. I recommend contacting a Private
Investigator if you want to trace someone. Sometimes it helps to have
an SSN, but the number isn't magic.

Dealing with Social Security

I'm an immigrant. How do I apply for an SSN?

My Social Security checks stopped coming. Who do I contact to
fix this?

This site is about Privacy and Social Security Numbers. The
Social Security Administration has a website where they have forms for
practically everything. They have their own FAQs, and these are both
likely to be found there.

In addition, you can reach the SSA by phone. They're in the
government section of every local phone book in the US.

Structure of the SSN

The details are available in this long description. The first three
digits reflect the location of the residence given on the application
for an SSN. They used to depend only on the SSA office that issued the
number. The SSA regularly publishes tables showing the
latest numbers being issued for each area.

There is a persistent rumor that the SSA encodes ethnicity in the
middle two digits. Most people have an even number as their fifth
digit, independent of ethnicity. This is because these numbers
are handed out in a strange sequence, and most regions of the
country haven't reached the odd numbers yet.